Having already a master degree will help in sorting in any of good mba college? And can a non-engineer apply in IIT's mba program?
Plus having b.sc gives you an advantage in IIMs because they give you extra marks in aggregate score for being non engineer and generally you get call for interview in low percentile than an engineer student of same category.
In IITs there might be a little problem as they prefer engineers over non engineers because they themselves are best engineering college in country.
But don't get upset because with your good academic records you have a very high chance to end up in good college like IIMs.
As less than a month is left for CAT exam so quickly brush up with your basics and start giving lots of online mock test and analyse them which will help you in overcoming your mistakes and come up with a strategy to attempt your paper which will definitely help you in improving your marks and percentile.
Aim for a high percentile It will make you convert a good college.
All the best for your preparations and exams!!